NASHVILLE, Tenn. (WZTV) - Doctors with the University of California are working to find out how a patient coughed up an intact blood clot.

The 36-year-old man was being treated for intensive heart failure before the episode according to the study published in the New England Journal of Medicine.

He had a pacemaker and heart pump placed in his body to assist with his heart issues.

The next week, doctors say the man suffered respiratory distress and was using oxygen. During an "extreme bout of coughing," the man coughed up a blood clot in the exact form of the right bronchial tree it had been blocking.

WARNING: Images might be consider too graphic for some viewers.

Doctors say while the episode caused the man to stop coughing up blood, he died from heart failure the next week.